Sebastian Vettel set the fastest time in Friday’s second Free Practice for the Korean Grand Prix, edging out Red Bull team mate Mark Webber by 0.032 seconds, with championship leader Fernando Alonso third.
The Red Bulls were three tenths quicker than their rivals at the head of the field to go into Saturday’s final practice and qualifying at Yeongam as favourites.
However, the McLarens and Ferraris weren’t too far behind in overall pace, with Mercedes also in the mix, to suggest there will be a close fight for the rest of the weekend.
“This afternoon the track was quite slippery to start with,” said Vettel. “But then I think it got a little bit better so, all in all, the car felt alright and now we see what we can do for tomorrow. I think we have to improve ourselves to match the others.”
Hamilton led the way in first Free Practice, but was at a loss to explain his lack of pace in the afternoon session where he finished eighth fastest, 0.885 seconds slower than pacesetter Vettel.
His McLaren team mate Jenson Button had a more positive day, finishing fourth fastest and was encouraged by his long-run pace following a race simulation at the end of the session.
Championship leader Alonso was pipped to the quickest time by Hamilton in the first session, but showed good pace in the second and was denied a quicker time after being held up by a HRT.
His Ferrari team light fuelled the car as they focused on improving their qualifying pace – which they have struggled with all season – and they appeared to make a step forward.
Their long-run towards the end of the session was also encouraging, and Alonso ended up third overall with team mate Felipe Massa sixth.
Lotus ran their new exhaust system on Kimi Raikkonen’s car with the Finn, who was racing in Korea for the first time, finishing 10th fastest, one place ahead of team mate Romain Grosjean.
Mercedes, who failed to score points with either car in Japan since the season opener in Australia, showed improved pace on the 5.615km circuit, with Michael Schumacher finishing fifth fastest, two places ahead of Nico Rosberg.
Having scored their fourth podium of the season in the Japanese Grand Prix with Kamui Kobayashi, Sauber struggled to replicate that form in Korea.
The Swiss team, who confirmed Monisha Kaltenborn as their new team principal on Thursday, taking over from owner Peter Sauber, saw Kobayashi and Sergio Perez finish 14th and 15th respectively.
Perez stopped midway through the session, when an actuator related to the engine failed. The team reported that there was no damage to the engine itself, but they were unable to get the Mexican back out on track.
With the circuit rarely used for most of the year, it took some time for the track to clean up and the first fast laps to come through.
Alonso set the early pace in the morning session, before Hamilton proved faster towards the end. In the afternoon, Vettel took top spot with 30 minute gone and held on as the rest of the field switched their focus to longer runs.
Conditions are expected to be warmer on Sunday than they have been in the previous two years the race has been held at Yeongam, with Pirelli predicting a two-stop race with around half a second between the soft and super-soft compounds.
KOREAN GRAND PRIX, Yeongam, Free Practice 2
1. Sebastian Vettel Red Bull 1m38.832 33
2. Mark Webber Red Bull 1m38.864s +0.032 33
3. Fernando Alonso Ferrari 1m39.160s +0.328 28
4. Jenson Button McLaren 1m39.219s +0.387 29
5. Michael Schumacher Mercedes 1m39.330s +0.498 31
6. Felipe Massa Ferrari 1m39.422s +0.590 30
7. Nico Rosberg Mercedes 1m39.584s +0.752 36
8. Lewis Hamilton McLaren 1m39.717s +0.885 25
9. Nico Hulkenberg Force India 1m39.739s +0.907 33
10. Kimi Raikkonen Lotus 1m39.839s +1.007 26
11. Romain Grosjean Lotus 1m39.957s +1.125 28
12. Bruno Senna Williams 1m40.089s +1.257 32
13. Paul di Resta Force India 1m40.112s +1.280 34
14. Kamui Kobayashi Sauber 1m40.445s +1.613 28
15. Sergio Perez Sauber 1m40.745s +1.913 11
16. Jean-Eric Vergne Toro Rosso 1m40.789s +1.957 31
17. Daniel Ricciardo Toro Rosso 1m40.997s +2.165 32
18. Pastor Maldonado Williams 1m41.200s +2.368 33
19. Heikki Kovalainen Caterham 1m41.602s +2.770 23
20. Timo Glock Marussia 1m42.596s +3.764 28
21. Charles Pic Marussia 1m43.066s +4.234 21
22. Vitaly Petrov Caterham 1m43.067s +4.235 22
23. Narain Karthikeyan HRT 1m43.869s +5.037 36
24. Pedro de la Rosa HRT 1m44.533s +5.701 24